Okay, looking to compare MPG notes with other 2006 & up 5 spd 5.7 ltr Dodge Charger owners. I have noticed a significant change in MPG since the gas changeover from summer to winter gas and since the weather change in October. So I wanted to find out what other owners are getting.

I use 93 octane and I get a solid 18.5mpgs with the stock goodyear tires on it. 26k on the clock.

Just put in an octane boost with my last full tank of 93. I would never put 87 in my tank. Honestly I would never put in lower than 91. It comes out to be a $2-$4 difference between a full tank of 87 compared to a full tank of 93.

I use 93 octane and I get a solid 18.5mpgs with the stock goodyear tires on it. 26k on the clock.

Just put in an octane boost with my last full tank of 93. I would never put 87 in my tank. Honestly I would never put in lower than 91. It comes out to be a $2-$4 difference between a full tank of 87 compared to a full tank of 93.

Without a tune you are not doing any good using anything above 89. (It will actually give you less power and MPG using a higher octane than needed)

As far as the octane boost, what are you hoping that will do?

Very few of them raise the octane more than a few points. A point is .1 octane, so using a booster that raises the octane 5 points may take you fuel from 91 to 91.5 They put some harmful stuff in most of those, too.

I was running 87 with a tune for 87, in my area the price differential has been more like $8/tank between 87 and 93. Finding 91 around here is rare. 87, 89 and 93 predominantly are what's available.

Without a tune you are not doing any good using anything above 89. (It will actually give you less power and MPG using a higher octane than needed)

As far as the octane boost, what are you hoping that will do?

Very few of them raise the octane more than a few points. A point is .1 octane, so using a booster that raises the octane 5 points may take you fuel from 91 to 91.5 They put some harmful stuff in most of those, too.

I was running 87 with a tune for 87, in my area the price differential has been more like $8/tank between 87 and 93. Finding 91 around here is rare. 87, 89 and 93 predominantly are what's available.

Switched over to my 93 tune today.

The manual right in your glove compartment suggests no lower than 89 octane fuel. That being factual, in my life I've been taught "high performance" vehicles call for high performance care. Which is why we run Synthetic Oils, or some members of the forum run the ACES fuel addatives.
It's just common practice for me, my family has owned powerful V8's forever. If the fuel is finer (thinner?) then naturally the gas will be of better quality and won't gunk up injectors and will burn cleaner providing better throttle response and more power. 93 with an octane boost is to clear the system because there isn't a higher octane available than 93, except close to racetracks.
It's more important WHERE you get your fuel rather than WHAT fuel you get. ExxonMobil and Shell are the best places. So my answer why run 93... For overall performance and health of my car, so it lasts longer.

That's just my opinion, you don't have to agree with it, I'm alright with what I'm doing.

The manual right in your glove compartment suggests no lower than 89 octane fuel. That being factual, in my life I've been taught "high performance" vehicles call for high performance care. Which is why we run Synthetic Oils, or some members of the forum run the ACES fuel addatives.
It's just common practice for me, my family has owned powerful V8's forever. If the fuel is finer (thinner?) then naturally the gas will be of better quality and won't gunk up injectors and will burn cleaner providing better throttle response and more power. 93 with an octane boost is to clear the system because there isn't a higher octane available than 93, except close to racetracks.
It's more important WHERE you get your fuel rather than WHAT fuel you get. ExxonMobil and Shell are the best places. So my answer why run 93... For overall performance and health of my car, so it lasts longer.

That's just my opinion, you don't have to agree with it, I'm alright with what I'm doing.

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Read your manual again. It says 87 is acceptable, 89 preferred.

The following is my opinion, based on experience:

Synthetic oil is no better than dino oil, this, based on years of having used oil analysis done with all kinds of oils. Walmart conventional "Supertech" is the cheapest oil you can buy, and performs remarkably well past 6k miles in my car. I generally use a full synthetic, for about 8k+

Fuel additives: The manual states not to use fuel additives. Many high performance publications, (That aren't benefiting from the makers of such product i.e. sponsorship/advertisement/partnerships) that additives are a waste of money and generally do more harm than good. No comment on the ACES other than I've tried it myself... I no longer use it.

Octane has ZERO relationship to cleaning ability. It is a measure of the resistance to detonate/knock. The higher the compression ratio, the higher octane you need. If you advance spark timing, you effectively increase compression ratio (not mechanically), and require a higher octane. (No need for high octane in our cars without a tune)
Higher octane fuel burns slower, which is basically how it resists detonating... without the higher compression, it may not fully burn, so you actually get less MPG and less power running too high of an octane fuel....

You live in NY, just like I do. NY years ago mandated all grades of fuel carry detergents. Used to be you only got that with premium, which is why all the "oldtimers" think you NEED premium, when they may not.

2006 LX/Charger manual, page 241:

"The 3.5L and 5.7L engines are designed to
meet all emissions regulations and provide
satisfactory fuel economy and performance
when using high-quality unleaded
gasoline with an octane rating of 87 to 89.
The manufacturer recommends the use of
89-octane for optimum performance. The routine use of
premium gasoline is not recommended. The use of
premium gasoline will provide no benefit over highquality
regular gasoline or mid-grade gasoline and in
some circumstances may result in poorer performance."

I have noticed a drop in my mpg with winter fuels
Year: 2007 5.7
Fuel being used: 89 octane
Current Mileage: 55,000
Type Of Tires being used: Michelin MXV4
Current Driving Pattern: Town driving 100% (not city not highway)
Current MPG average on EVIC: 13.7 MPG

I like to use Autostick at times and enjoy my rides, so I guess you can call it a bit of spirited driving.

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Winter fuel mileage drop would more likely be related to the blending in of ethanol. In my 3.6 I have also seen a difference on the same tank of gas, no mods, or fancy stuff, with decreased temperature. Happens also with mods and fancy stuff, so I think it has something to do with the fuel trim and a big temp swing.

I use 93 octane and I get a solid 18.5mpgs with the stock goodyear tires on it. 26k on the clock.

Just put in an octane boost with my last full tank of 93. I would never put 87 in my tank. Honestly I would never put in lower than 91. It comes out to be a $2-$4 difference between a full tank of 87 compared to a full tank of 93.

What manual are you reading? The 5.7L hemi was optimized for 87-89, or it wouldn't say it in the manual.

Honestly I switch between 91 or 93 depending on if the station I'm at carries 93 (Shell does). But the reason for that is Regular: 87[$3.99], Premium: 89[$4.19], Super: 91[$4.39], Shell V-Power: 93[$4.41]… Prices are pretty close and it will save me from having to use high octane later mileage wise.

When I used 87 in my last Hemi, it dealt with it okay, but it felt resistent a lot of the time. I can literally 'feel' the difference between Regular and Super. Explain how I lose power by using a fuel that I've experienced more power using, please.

Also, with my last hemi I saw no change in MPGs using 93 compared to 87 or 89. That was a comparison Stock and with my Tuner on "Tow/Hall, Performance 91, 87 and Mileage XS" using different types of gas from mom+pop stations, to Stewarts, to Shell, to Sunoco, to Xtra Mart. And my conclusion was... 91-93 octane from Mobil(i.e. Xtra Mart) and from Shell gave me the most responsive throttle, the most power and no difference in gas mileage. So, I will not be swayed to use a lower grade of fuel. It works for me and I don't have a problem being alienated for it. You use what you use, I'll use what I use fellas.